1. Field of the Invention
This invention relates generally to techniques of controlling loop gain, and more particularly, to a system and method of controlling loop gain in an optical wireless link based on distance.
2. Description of the Prior Art
An optical wireless link system consists of two stations: a transmitter and a receiver. The transmitter is able to change the direction of its transmitted beam by known amounts of angular displacement. The receiving station sees this motion and sends position correction information back to the transmitter. The amount of motion seen by the receiver depends on the spacing between the transmitting and receiving stations. The amount of beam motion will vary by a factor of 50 for units whose range can vary from 1 to 50 meters. The loop gain of the control system will likewise vary by that same factor of 50. This gain variation is well beyond the range that typical control techniques known in the art can handle while maintaining optimal performance. Setting the gains for use at short range will result in an unstable system when used at long range. Using the long range gains at close distance will render sluggish system response. In view of the foregoing, it would be desirable and advantageous in the optical wireless communication art to provide a technique that allows an optical wireless communication link to be used reliably over a wide range of distances.